Which of the following numbers are squares of even numbers?

$841$

Which of the following numbers are squares of even numbers?

$2,304$

Using a suitable pattern, evaluate the following:

$(999999{)}^2$

Using a suitable pattern, evaluate the following:

$(99999999{)}^2$

Using a suitable pattern, evaluate the following:

$(111111{)}^2$

Using a suitable pattern, evaluate the following:

$(66666667{)}^2$

Using a suitable pattern, evaluate the folowing:

$(6667{)}^2$

Give reasons why the following numbers are not perfect squares.

$23,647$

Give reasons why the following numebrs are not perfect squares.

$14,080$